The present invention relates to medical devices and procedures. More particularly, the present invention relates to a method and apparatus for percutaneous introduction of an endoluminal stent or stent graft that is particularly suited for percutaneous delivery of bifurcated stents or stent grafts into the vascular system of a patient.
Transluminal prostheses for implantation in blood vessels, biliary ducts, or other similar organs of the living body are, in general, well known in the medical art. For example, prosthetic vascular grafts formed of biocompatible materials (e.g., Dacron or expanded, porous polytetrafluoroethylene (PTFE) tubing) have been employed to replace or bypass occluded or damaged natural blood vessels. Examples of prosthetic vascular grafts are described in U.S. Pat. No. 4,955,899 (issued to Della Coma, et al. on Sep. 11, 1990); U.S. Pat. No. 5,152,782 (Kowligi, et. al., Oct. 6, 1992).
A form of transluminal prostheses, used to maintain, open, or dilate tubular structures or to support tubular structures, is commonly known as a stent, or when covered or lined with biocompatible material, as a stent-graft or endoluminal graft. In general, the use of stents, and stent-grafts for treatment or isolation of vascular aneurysms and vessel walls which have been thinned or thickened by disease (endoluminal repair or exclusion) are well known.
Many stents and stent grafts, are "self-expanding", i.e., inserted into the vascular system in a compressed or contracted state, and permitted to expand upon removal of a restraint. Self-expanding stents typically employ a wire of suitable material, such as a stainless steel, configured (e.g. bent) to provide an outward radial force, and/or formed of shape memory wire such as nitinol (nickel-titanium) wire. When the shape memory wire is employed, the stent is typically of a tubular configuration of a slightly greater diameter than the diameter of the lumen, e.g., blood vessel, in which the stent is intended to be used. The stent may be annealed at an elevated temperature and then allowed to cool in air so that the shape memory wire "remembers" the initial configuration. The shape memory wire is suitably martensitic at room temperature, austenitic at typical body temperature. For example type "M" nitinol wire is martensitic at temperatures below about 13.degree. C. and is austenitic at temperatures above about 25.degree. C.; type "M" wire will be austenitic at body temperature of 37.degree. C. Such nitinol wire is "super elastic" in its austenitic state; the radial outward force exerted by the stent on the wall of the lumen, (e.g., blood vessel) is therefore substantially constant irrespective of the diameter of the vessel and the expanded stent.
Various forms of stents and/or stent grafts are described in U.S. Pat. Nos. 5,873,906 (issued to Lau, et. al. on Feb. 23, 1999); 5,302,317 (Kleshinski, et. al., May 11, 1999); 5,662,713 (Andersen, et. al., Sep. 2, 1997); 5,575,816 (Rudnick, et. al, Nov. 19th, 1996); 5,0507,767 (Maeda, et. al, Apr. 16th, 1996); 5,415,664 (Pinchuk, May 16, 1995); 4,655,771 (Wallsten, Apr. 7, 1987); 4,800,882 (Gianturco, Mar. 13, 1987); 4,907,336 (Gianturco, Sep. 9, 1988); and 5,718,724 (Goicoechea, Feb. 17, 1998).
In general, stents and stent grafts are deployed either by a "cut-down" procedure, i.e., cutting directly into the lumen from an entry point proximate to the site where the prosthesis is to be deployed, or through a less invasive percutaneous intraluminal delivery, i.e., cutting through the skin to access a lumen e.g., vasculature, at a convenient (minimally traumatic) entry point, and routing the stent graft through the lumen to the site where the prosthesis is to be deployed.
Intraluminal deployment is typically effected using a delivery catheter with coaxial inner (plunger) and outer (sheath) tubes arranged for relative axial movement. The stent is compressed and disposed within the distal end of the outer catheter tube in front of the inner tube. The catheter is then maneuvered, typically routed though a lumen (e.g., vessel), until the end of the catheter (and thus the stent) is positioned in the vicinity of the intended treatment site. The inner tube is then held stationary when the outer tube of the delivery catheter is withdrawn. The inner tube prevents the stent from being withdrawn with the outer tube, so that, as the outer tube is withdrawn, the stent radially expands into a substantially conforming surface contact with the interior of the lumen e.g., blood vessel wall. An example of such a delivery system is described in aforementioned U.S. Pat. No. 4,655,771 (Wallsten, Apr. 7, 1987).
Other more specialized forms of delivery systems are also used. For example, U.S. Pat. No. 5,415,664 issued to Pinchuk on May 16, 1995, describes a stent delivery and deployment apparatus including three concentric tubes: an interior hollow tube and an outer sheath (generally corresponding to the inner and outer tubes of the delivery system described above); and an inner tubular actuation member with a cup-like gripping member rigidly attached to the distal end thereof. Relative movement between the interior tube and the actuation member provides a selectively actuable clamping or gripping mechanism between the cup-like member and the end of the interior tube. The end of a stent or stent-graft is inserted into the cup-like member and clasped between the cup-like member and the end of the interior tube. The distal end of the introducer is inserted into the sheath and pulls the distal end of the stent into the sheath, thereby stretching and radially compressing the stent to a reduced diameter. The sheath containing the stent and the remainder of the introducer is maneuvered to the site for deployment of the stent. The introducer is held in a stationary position and the sheath is pulled partially back towards the proximal end of the introducer so that a middle portion of the stent is released from the sheath. The introducer, stent, and sheath can then be moved to precisely locate the stent before it is deployed. When the stent is in a precise desired location, the introducer is held in a stationary position and the sheath is pulled back further to release the proximal end of the stent. The distal end of the stent is then released from the cup-like cap member and the distal end of the hollow tube. The introducer is then removed through the lumen of the expanded stent.
Other devices for deploying self-expanding endoprosthesis are described in: U.S. Pat. No. 5,484,444 issued to Braunschweiler, et. al., on Jan. 16, 1996, (including a mechanism for recompressing and recapturing the endoprosthesis within an outer sheath to facilitate repositioning and extraction) and U.S. Pat. No. 5,833,694 (Poncet, Nov. 10, 1998) (including a mechanism for deploying multiple stents at multiple sites within a body passage without completely withdrawing any part of the deployment device from the patient's body); and 5,776,142 (Gunderson, Jul. 7, 1998) (including a mechanism for controlling axial movement of the ends of the stent towards each other while simultaneously controllably rotating the ends of the stent about the longitudinal axis to provide for its controlled radial expansion); and U.S. Pat. No. 5,700,269 (Pinchuk, et. al., Dec. 23, 1997) (including mechanism for retracting the stent).
The use of trigger or release wires to control expansion of self-expanding endoprosthesis are also known. For example, such a system is described in U.S. Pat. No. 5,019,085 issued to Hillstead on May 28, 1991. A stent is disposed on the exterior of the distal end of a catheter. An elongated wire is inserted down the catheter's passageway then routed outside the catheter through an opening in the catheter sidewall. The wire is then looped over the stent, and routed back into the catheter interior through a second opening in the catheter sidewall. The wire is routed through the catheter interior passageway to a third opening in the catheter sidewall where it is again routed outside the catheter's passageway to loop over a distal end of the stent. The wire is then inserted back into the catheter. The wire holds the stent compressed against the catheter wall as it is delivered to a desired position. When the stent is positioned at the desired deployment site, the stent is released by withdrawing the wire from the catheter a distance sufficient to free one end of the stent. The stent is then free to expand into an uncompressed state even though the wire still engages the stent at its proximal end. If in the physician's opinion, the stent has been properly positioned, continued withdrawal of the wire from the catheter completely frees the stent from the catheter and the catheter is withdrawn. If, however, the stent is improperly positioned, the wire can be held in place to retain the stent as both catheter and stent are withdrawn from the subject.
The aforementioned U.S. Pat. No. 5,873,906 to Lau, et. al., discloses another delivery system wherein a tether line is employed to maintain the stent or stent-graft in a folded configuration until release. The stent is deployed in a body lumen or cavity using a catheter comprising an interior tube (guide wire tubing) and an outer sliding sheath. The stent graft is placed between distal and proximal barriers fixed on the interior catheter (to hold the stent graft in axial position prior to deployment), with the catheter interior tube within the lumen of the stent graft. The stent or stent-graft is then, in effect, flattened and folded (wrapped) around the catheter inner tube. Two sets of loops are provided on the outer jacket of the stent graft, disposed so that they are in juxtaposition (in general linear alignment) when the stent graft is flattened and wrapped around the catheter. The tether wire is threaded through the respective sets of loops to hold the stent graft under compression i.e., folded, on the catheter. The tether wire is run through the exterior sheath of the catheter in parallel to interior tube. After the stent graft is placed in position, the tether wire is removed by sliding it axially along the stent and out of the loops so that the stent unfolds into a generally cylindrical shape within the body lumen or cavity.
The application of stent grafts to branched lumen (such as the infrarenal portion of the aortic artery where it bifurcates to the common iliac arteries) is also known. However, the deployment of a bifurcated stent is typically relatively invasive. For example, some bifurcated stents involve respective portions that are joined in situ and require a plurality of catheterizations are described in U.S. Pat. Nos. 5,916,263 (issued to Goicoechea, et al. on Jun. 29, 1999); 5,906,641 (Thompson, et. al., May 25, 1999); 5,695,517 (Marin, et. al., Dec. 9; 1997); 5,632,763 (Glastra, May 27, 1997); 5,609,627 (Goicoechea, et al., Mar. 11, 1997); and 5,316,023 (Palmaz, et. al., May 31, 1994).
It is also known to insert and advance a unitary bifurcated graft through a single branch of the femoral arterial system, to a point beyond the treatment site, then pull or draw one of the limbs into the contralateral (opposite) branch by significant and skillful manipulation of a contralateral-femoral wire catheter or snare. Such a system is described in U.S. Pat. No. 5,639,278 issued to Dereume, et. al., on Jun. 17, 1997. Other deployment systems require cross-femoral wire catheter and guidewires, such as described in U.S. Pat. No. 5,489,295 (Piplani, et. al., Feb. 6, 1996), and PCT Application WO 98/36708 (Endologix, published Aug. 27, 1998). In each case, catheterization in both femoral arteries is required.
It has also been suggested, U.S. Pat. No. 4,617,932 (Kornberg, Oct. 21, 1986), that blood flow entering the graft, can be utilized to cause the contralateral leg of a graft to float free in the blood stream so that it may be directed to the proper position.
Other stents for bifurcated lumen are deployed from the trunk (proximal) lumen e.g., the heart side of iliac arteries. Examples of such stents grafts are described in U.S. Pat. No. 5,906,640 issued to Penn, et. al., on May 25, 1999; U.S. Pat No. 5,755,734 issued to Richter, et. al., on May 26, 1998; U.S. Pat No. 5,827,320 issued to Richter, et. al., on Oct. 27, 1998. These devices, however, cause more trauma to the patient as they require large access ports in a portion of the vessel that is usually much deeper under the skin than the preferred femoral artery entry site.
Accordingly, there is a need for a deployment system that permits accurate placement of a stent graft without inordinate complexity, and for deploying bifurcated stents and stent grafts without requiring more than one catheterization. Further, it is desirable that the diameter of the compressed stent and insertion apparatus be as small as possible to facilitate insertion, particularly in smaller lumens, and to minimize trauma to the lumen. Accordingly, a stent that can be deployed without requiring the additional thickness of an external catheter would be desirable.